1. Field of the Invention
The present invention relates to a parallel hybrid vehicle in which an engine, and an electric motor serving also as a generator are provided and output torques of the engine and the motor are transmitted to a transmission through a torque combining mechanism constituted of a planetary gear mechanism to produce a running driving force from one or both of the engine and the motor.
2. Description of the Related Art
One of the conventional parallel hybrid vehicle has been disclosed in Japanese Patent Application Laid-Open No. Heisei 10-304513 (corresponding to U.S. Pat. No. 6,054,776). Disclosed in the above-identified publication combines an output torque of an engine and an output torque of an electric motor are combined by a torque combining mechanism constituted of a planetary gear mechanism to transmit the combined torque to a driving wheel via a transmission. In the parallel hybrid vehicle, for example, upon acceleration from standstill condition, a motor generator having large torque at low speed range is used as a motor, subsequently, the output torque of the motor generator and the output torque of the engine are combined, and at further high speed region, the motor generator is turned off to drive only with the output torque of the engine. In such parallel hybrid vehicle, when the motor speed of the motor generator reaches an engine speed, both, more particularly respective elements of the planetary gear mechanism connected to both are directly connected by a direct connection clutch to enhance response characteristics of output torque control. On the other hand, upon deceleration state of the vehicle, the motor generator is driven by a reaction torque input from a road surface to operate the motor generator as a power generator to accumulate electric power. Such operation is referred to as regeneration. In this case, when the engine and the motor generator are directly connected, regeneration efficiency is lowered by engine braking effect. Therefore, the direct connection clutch may be disengaged. Conventionally, the direction connection clutch is typically constructed by a hydraulic clutch.
However, the hydraulic clutch to be used as the direct connection clutch in the conventional parallel hybrid vehicle is not high in response characteristics in engaging and disengaging. Therefore, in the case that the direct connection is disengaged when the motor generator is regenerated, it may be taken a time for disengaging the direct connection clutch, and energy may not be collected until regenerating operation is initiated to lower regeneration efficiency. On the other hand, the hydraulic clutch is required to arrange a plurality of friction plates in axial direction, for example, to make it impossible to shorten the length in the axial direction. Also, the hydraulic clutch is restricted significantly in layout since the hydraulic path for actuating the piston and so forth has to be formed.
The present invention has worked out in view of the problems set forth above. It is therefore an object of the present invention to provide a parallel hybrid vehicle which can improve regeneration efficiency upon regenerating operation by employing an electromagnetic two-way clutch which is superior in engaging and disengaging, can shorten a length in axial direction and can provide great freedom in layout.
According to one aspect of the present invention, a parallel hybrid vehicle comprises:
an engine;
a motor generator having both functions of a generator and a motor;
a transmission;
a torque combining mechanism combining an output torque of the engine and an output torque of the motor generator by a planetary gear mechanism for outputting torque;
control means for controlling output torque of the motor generator and rotating condition; and
an electromagnetic two-way clutch mechanism selectively controlling engaging and disengaging of between respective elements of the planetary gear mechanism.
The electromagnetic two-way clutch is formed with the inner ring and the outer ring arranged across the rolling element, such as the roller, and one of rolling contact surfaces mating is formed as cam face, and the other rolling contact surface is formed as cylindrical surface. The electromagnet is energized for integrating one of the inner ring and the outer ring carrying the cam face and a cage. Then, the rolling element is engaged between the cam face and the cylindrical surface of the inner and outer rings for integral rotation of the inner and outer rings. On the other hand, when the electromagnet is deenergized, namely turned off, the cage is integrally rotated with one of the inner and outer rings carrying the cam face to place the rolling element at the neutral position between the cam face and the cylindrical surface and whereby to permit relative rotation of the inner and outer rings. Namely, when the rolling element is engaged between the cam face and cylindrical surface to integrate the inner ring and the outer ring, the electromagnetic two-way clutch is engaged, and when the rolling element is integrated one of the inner and outer rings carrying the cam face to permit relative rotation of the other inner and outer rings, the electromagnetic two-way clutch is disengaged.
The planetary gear mechanism of the torque combining mechanism and the motor generator may be separated by a partitioning wall coupled with the transmission, the partitioning wall being reduced in diameter at an end portion on the side of the motor generator, an electromagnet of the electromagnetic two-way clutch is arranged on inside of diameter reduced portion of the partitioning wall.
A sun gear of the planetary gear mechanism of the torque combining mechanism may be connected to the motor generator, a ring gear is connected to the engine, a pinion carrier is connected to the transmission, and the sun gear and the pinion carrier of the planetary gear mechanism is engaged and disengaged by the electromagnetic two-way clutch.
When the electromagnetic two-way clutch is shifted from engaged position to disengaged position, the control means deenergize the electromagnet of the electromagnetic two-way clutch and controls an output torque of the motor generator so that revolution speed of the motor generator becomes higher than revolution speed of the engine.